Coulomb's Constant Explained

Coulomb's constant is used in the electrostatic force equation and is one of the fundamental electromagnetic constants of our universe that include:

speed of light
magnetic permeability
electric permittivity

These values are all related by the free space calculations in the SI system with the expression:

Coulomb's constant, speed of light, magnetic permeability, electric permittivity

Electrostatic Force

Coulomb's constant is used throughout electrostatic calculations, including Coulomb's Law, electric potential energy and electric field strength.

The calculated value is:

In university we were taught an easy way to remember this value as '9 times 10 to the 9th'.

Electrical engineering consultants rarely use Coulomb's constant when designing electrical distribution systems because the mathematics for electromagnetism has either been incorporated into our tables and graphs or our work doesn't involve electrostatics and single point charges.